Conventionally, the small-sized pump disclosed in PTL 1 has been known as an air pump used for a sphygmomanometer and the like, for example.
The small-sized pump is provided with a plurality of diaphragms for forming a pump chamber in the case. A cylindrical exhaust valve is formed at a center portion of the pump chamber. In addition, the pump chamber is provided with a suction valve. The diaphragms are connected with a swing member, and are vertically moved when the swing member swings with an eccentric rotation shaft. The eccentric rotation shaft is fixed with eccentricity to a disk part fixed to the rotation shaft of a DC motor disposed below the eccentric rotation shaft.
In the small-sized pump, when the DC motor is driven into rotation, the eccentric rotation shaft rotates with eccentricity to swing the swing member and vertically move the diaphragms in an alternate manner, thus performing suction from the suction valve and exhaustion from the exhaust valve. That is, in the small-sized pump, the rotation of the DC motor that performs typical axial rotation is converted into precession with use of the eccentric rotation shaft and the swing member in order to vertically move the diaphragms.
Known examples of the driving part for precession include the biaxial type actuator disclosed in PTL 2 and the swing driving apparatus disclosed in PTL 3.
The actuator of PTL 2 is used for a holography apparatus, which adjusts the incident angle of reference light with respect to the optical recording medium by setting the reflection mirror at a desired inclination angle. To be more specific, the actuator includes a movable shaft for supporting the control object, and a support mechanism for swingably supporting the movable shaft with respect to a third axis (Z axis) as a reference shaft that is perpendicular to a first virtual axis and a second virtual axis orthogonal to each other. With use of a magnetic circuit composed of a magnet and a coil, the movable shaft is tilted relative to the orientation that coincides with the reference shaft.
In addition, PTL 3 discloses a swing driving apparatus for swinging an antenna used in the space. PTL 3 discloses an elastic support mechanism disposed between an antenna and a seat for supporting the antenna on the back side. The elastic support mechanism supports the antenna at a center point on the back side, and swingably mounts the antenna around two axes orthogonal to each other. The elastic support mechanism is formed of an elastic material, and includes an elastic shaft whose one end is fixed at a center of the back of the antenna and the other end is fixed to a center of the seat, and leaf springs that are disposed at approximately 90 degrees with respect to each other and whose one end is fixed to at a center of the back of the antenna and other end is fixed at four points on the seat. The antenna swings by the actuator that exerts a force on the antenna supported by the elastic support mechanism.